Region and Crop Type Influenced Fungal Diversity and Community Structure in Agricultural Areas in Qinghai Province

The differences in soil fungal communities in four agricultural areas growing wheat (Triticum aestivum), rapeseed (Brassica napus), and barley (Hordeum vulgare) in the Qinghai Province, namely the Dulan (DL), Gonghe (GH), Huzhu (HZ), and Datong (DT) counties, were investigated using high-throughput sequencing. The region showed highly significant effects on soil pH, organic matter, ammonium nitrogen, nitrate nitrogen, total phosphate, effective phosphate, total sulfur, and effective sulfur (p < 0.01). The crop type resulted in highly significant (p < 0.01) variations in total phosphate and effective phosphate. Principal coordinates analysis and nonmetric multidimensional scaling revealed significant differences in soil fungal diversity and fungal community composition in the soils of three crops or four regions (p < 0.05). Although the soils of the four regions or three crops had similar dominant phyla, classes, and genera, these taxa differed in terms of their relative abundance. Four, 12, 15, and 16 biomarkers with significant linear discriminant analysis effect sizes were identified in the HZ, DL, GH, and DT groups, respectively. A total of 36, 12, and eight significant biomarkers were observed in the wheat, rapeseed, and barley soils, respectively. In addition, altitude and soil physicochemical properties had significant relationships with fungal diversity and community composition (p < 0.05, p < 0.01).